The purpose of this project is to develop a set of psychophysiological measures which can be used to predict clinical response to stimutant drug medication in minimal brain dysfunctioned children prior to a clinical trial of medication. A variety of averaged evoked potential (AEP) and EEG measures are obtained under task and no task conditions after the child has taken a single oral dose of Ritalin or placebo. Psychological and neurological abilities are also assessed. Following completion of this testing, children are placed on 10 mg of Ritalin BID and the dosage adjusted until a good clinical response is obtained. Teacher and parents then make daily ratings of the child's school and home behavior over a 10 day period in which placebo and Ritalin capsules are randomly given to the child. Parents and teachers do not know which drug the child has taken on any particular day. At the conclusion of this double blind period the supervising pediatrician, without knowledge of the AEP or 10 day double blind results, evaluated the degrees of improvement each child had shown over the course of therapy. A number of differences in the pre-clinical trial assessment statistically discriminated hyperactive children who showed the greatest degree of clinical improvement from those who showed minor changes. Greatly improved children had more variable visual evoked potentials, showed AEP attentional deficits when placebo was given that appeared to be "corrected" in the Ritalin run, and had higher full scale WISC IQ's. We are currently working on the joint effect of distraction, attention and drugs on hyperactive AEP's.